Functional Characteristics of a Novel Chemosensory Protein in the Cotton Bollworm Helicoverpa armigera (Hübner)
ZHANG Tian-tao, WANG Wei-xuan, ZHANG Zi-ding, ZHANG Yong-jun , GUO Yu-yuan (1.Key Laboratory for Bio-Resource and Eco-Environment, Ministry of Education/State Key Laboratory of Hydraulics and Mountain River Engineering/College of Life Science, Sichuan University, Chengdu 610064, P.R.China 2.Neijiang Hybrid Rice Research and Development Center, Neijiang 641000, P.R.China 3.Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow 83844, USA 4.School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei 230009, P.R.China)
A chemosensory protein named HarmCSP5 in cotton bollworm Helicoverpa armigera (Hübner) was obtained from antennal cDNA libraries and expressed in Escherichia coli. The real time quantitative PCR (RT-qPCR) results indicated that HarmCSP5 gene was mainly expressed in male and female antennae but also expressed in female legs and wings. Competitive binding assays were performed to test the binding affinity of recombinant HarmCSP5 to 60 odor molecules including some cotton volatiles. The resules showed that HarmCSP5 showed strong binding abilities to 4-ehtylbenzaldehyde and 3,4-dimethlbenz aldehyde, whereas methyl phenylacetate, 2-decanone, 1-pentanol, carvenol, isoborneol, nerolidol, 2- nonanone and ethyl heptanoate have relatively weak binding affinity. Moreover, the predicted 3D model of HarmCSP5 consists of six α-helices located among residues 33-38 (α1), 40-48 (α2), 62-72 (α3), 80-96 (α4), 98-108 (α5), and 116-119 (α6), two pairs of disulfide bridges Cys49-Cys55, Cys75-Cys78. The two amino acid residues, Ile94 and Trp101, may play crucial roles in HarmCSP5 binding with ligands and need further study for confirmation.
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